ABCD

Example

A
B
A
8
B
B
C
17
B
C
C
_
13
_
11
 
 
A
B
C
_
_
_

Solution

A
B
A
8
B
B
C
17
B
C
C
16
13
17
11
 
 
A
B
C
1
6
5
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ABCD
ABCD

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